YML-file and upload What is it and how to use
With the advent of the ability to upload and download data to the site, the life of online stores has become much easier. How easy it is now to migrate e-commerce from site to site with your products.
Saving valuable time - that's why you need to set up all kinds of exports of popular formats, including YML. For those who are not at all in the subject, let's start from the basics.
YML format
Yandex isotope of XML format. It is a widely used markup language that almost any system can understand today. With its help, information gains structure. In fact, it frames the data in tags that describe where and how this data should be located, what it means, and in general, whatever. And the best thing is the ability to create your own tags, which they used in Yandex and actually created their own markup standard, convenient for moving goods from stores to their Market and vice versa, as well as between all sorts of sites. I must say, users love it very much, and they are willing to use the capabilities of YML.
What is YML unloading for?
As you already understood, the main function of such an export is its subsequent transfer to other services and platforms, primarily to Yandex.Market.
Imagine that people would send files to the Market each in the form in which he maintains it: in an Excel spreadsheet with his own headers, someone observing the cell formats, and someone not, maybe not in Excel at all ... How many it would take years for specialists to sort out this chaos. Fortunately, there is standardization, and everyone loads everything beautifully, in a unified form, and gets it beautifully too, exactly as they wanted (the name of the categories, the price, etc. - all their own). You can, of course, upload tabular formats, but you have to greatly limit your imagination.
The pros of YML are obvious:
- You don't add products manually
- No need to hire a person or waste time on posting all information about commodity items
- The same format can be used for different sources. Already having a YML document, you often don't even need to create XML
- Integration with many advertising systems, aggregators will also be painless for you
- When generating a YML export file on the site, you can forget about tracking and manually updating prices. OkayCMS has already implemented this functionality in the Pro version and even in Lite (where have you seen this at all?)! You can use it simply from the admin panel by selecting all or certain products. The feed (generated file) will be available at: https://demookay.com/yandex.xml
By uploading yml-documents, you can also store your information, making a kind of backups. If some Internet source suddenly stops working, you will be left with a ready-made document, which will also be easily restored and converted later.
It is convenient to exchange price lists with YML partners by integrating them into your system. Here, this format is good because you do not need to download anything, get confused in several documents or wait for something to be sent to you by mail, it is enough to get a link once.
How to unload products from a website to Yandex.Market
The export procedure for versions 1 * is described here . After the update, the system has improved in terms of export, but the logic remains the same and is still intuitive. In the admin panel, go to the tab with products and on the right, click on the XML icon opposite the product that needs to be unloaded. 
You can also use a filter to find those positions that are already on the Market or vice versa. 
You can combine brands and categories in filters with participation in the Market.
All selected products will go to the feed. To view it, add / yandex.xml to your domain You just copy and paste this link wherever YandexMarket asks you. That's all, it doesn't hurt at all!
If you are not a happy owner of OkayCMS, but an unfortunate user of some other system, then it's not too late to change your mind :-)
Then the best solution would be to contact a specialist or, having clearly followed the training recommendations of Yandex , try to upload your creation to their site.
YML example
Yandex Help has a soulless YML file template. But we are not greedy, we can share our demo document to understand how a beautiful and correct generated upload file should look like: https://demookay.com/yandex.xml
What mistakes can be in YML
Yandex gives rather detailed descriptions of both the requirements and the possible errors themselves. You can get acquainted with them in the help. They are also unlikely to deny you support, but be sensible and read the documentation first.
Okay website owners may not think about mistakes, because YML unloading is automatic , but let's list the main points in which these errors can occur:
- non-compliance with XML specifications. You can check by changing the extension to .xml and looking in the browser or running it through the validator;
- non-compliance with the requirements for the YML format (elements are used incorrectly or in the wrong order, there are empty ones, there are no required ones, there are invalid characters);
- wrong encoding. UTF-8 and windows-1251 are accepted;
- repeated id (that's what it is to be unique);
- problems with the URL (lead to a non-existent file, have Cyrillic characters, spaces). You need to pay attention to the protocol and www
located on a subdomain or another site.
In general and in general, you must first of all comply with the conditions for placing your store on the Yandex site. Not having everything that the agreement requires, is it worth bothering with drawing up a yml-price for the Market.
Bonus - non-standard use of YML markup
Yandex gave people an excellent opportunity to use the Webmaster and even with its help to improve the display of their product pages in search results for free. By uploading the YML file (by pasting the link and clicking "Add") here 
update the status and after checking, click the green checkmark if it was successful. You can also find out the reason if the check shows an error. The result of all the torment will be attractive snippets with a price in Yandex search results.
So, we learned that YML unloading is a useful thing in every way. Do not give up such a convenient functionality and do not forget that we still have a lot of cool features!